The invention relates to a crane, in particular a bridge crane or gantry crane, having at least one horizontally extending crane girder designed as a lattice girder having a plurality of struts, on which crane girder a crane trolley with a hoist can travel, wherein at least some of the struts have a sheetlike flat design and the flat struts each comprise a planar main surface which extends in each case transversely to a longitudinal direction of the crane girder.
A crane of this type is known from the German laid-open document DE 10 2012 102 808 A1. In this connection, the struts are disposed in pairs in the shape of a pitched roof and a vertically extending post is provided between the struts of each pair of struts. An upper boom and a lower boom of the crane girder are connected to one another via the struts and the posts. Furthermore, the struts have long sides with bent edges for stiffening purposes. The bent edges of the long sides mean that side surfaces are formed between lower first and upper second recesses and adjoin the main surfaces as so-called anti-buckling means, are bent at approximately a right angle with respect to the main surfaces and are oriented transversely to the longitudinal direction of the crane girder.
In relation thereto, the supporting elements of a lattice construction which extend in an inclined or diagonal manner are generally considered to be struts. In this way the struts of a lattice construction differ from the supporting elements which extend purely vertically and are referred to as posts. Furthermore, the flat struts or planar struts preferably absorb forces in the direction of their longitudinal axis and therefore in the plane of extension of their planar main surface. Flat elements or flat supporting structures of this type are referred to in mechanics as disks, whereas flat elements loaded perpendicularly to their plane of extension or main surface are referred to as plates. Disks and therefore also the present planar struts differ e.g. from bars or bar-like posts and struts in that their thickness dimensions are substantially smaller than the length and width dimensions determining the planar extension of the disks. Consequently, flat struts are also referred to as planar struts or disk struts.
From US 2011/0247993 A1 a bridge crane is known having a crane girder designed as a lattice girder and comprising rod-like struts in a paired X-shaped arrangement.
DE 32 22 307 A1 discloses a bridge girder designed as a lattice girder, the flat struts of which are arranged in a paired x shape.
Further lattice girders are known from U.S. Pat. No. 327,360 A and DE 1 907 455 A.